Condenser structure



A. E. FERRET CONDENSER STRUCTURE March 29, 1938.

Filed June 26, 1954 1 A TTORNLY UNITED STATES PATENT OFFICE CONDENSER STRUCTURE Albert E. Ferret, New York, N. Y., aasignor, by

mesne assignments, to Electro-Mechanical Research Ina, Brooklyn. N. Y., a corporation of New York Application June 2c, 1934. Serial No. 732,419

2 Claim. This invention relates to condensers and with particularity to an improved form of adjustable or variable condenser.

A principal object of the invention is to provide 5 a rugged and highly eflicient variable condenser.

Another object is to provide an improved structure for trimmer condensers, Vernier condensers or the like.

In certain fields of use, for example aboard moving vehicles or the like, condensers are subjected to a great amount of mechanical vibration and in some instances to rapid or excessive perature changes, as a result of which the trostatic capacity of the condenser varies time to time from. the desired or set value. 'cordingly, another object of this invention provide an adjustable or variable condensertemelecfrom Acis to which retains its permanency of setting regardless of mechanical vibrations, temperature changes or the like.

A feature of the invention relates to an adjustable or variable condenser of rugged construction and having a minimum of electrical losses.

Another feature relates to a trimmer, vernier or similar adjustable condenser having a ratio of maximum to minimum capacity.

high

A further feature relates to the novel organization, arrangement and relative location of parts which go to make up an eflicient and reliable variable condenser which is capable of economical manufacture.

I "Other features and advantages not specifically enumerated wil1 be apparent after a consideration of the following detailed descriptions and appended claims:

and not by way of limitation.

In the drawing, Fig. 1 is a perspective view of a trimmer condenser orsimilar adjustable denser embodying features of the invention.

Fig. 2 is a sectional perspective view of the structure shown in Fig. 1,'taken along the plane A-A thereof.

Fig. 3 is a detail view showing the manner in which the condenser electrodes are guided and locked.

Fig. 4 is a top plan view of the main insulating support or base of the condenser. Fig. 5 is an end view of Fig. 4.

Fig. 6 is a detail plan view of one of the dielectric spacers.

Fig. '7 is a detail view of one of the cond electrodes.

. general shape shown in Fig. 6.

Referring more particularly to Figs. 1, 4 and 5, the numeral i indicates a block of suitable insulating material which is preferably molded to the shape shown and is preferably constituted of an insulating material having a minimum of dielectric losses; As shown the base is formed with a flat portion 2 and side portions 3 and 4. Each of the side portions is formed with a bossl provided with a bore or perforation 6 for fastening the assembled condenser to a suitable support. The base I is also provided on opposite faces with sets of aligned bosses I, 8, 9 and [0, ll, l2, which define rails or grooves on opposite faces of the base for purposes to be described. Rigidly fastened in the base I, preferably by being molded therein, is a hollow metal member II which is threaded both internally and externally.

The conducting layers or electrodes of the condenser are of the general shape shown in Fig. '7, while the spacer or dielectric members are of the In accordance with conventional condenser design, the metal electrodes are separated by the dielectric mem-' bers, and in order to enable the capacity to be varied or adjusted, alternate metal electrodes are bowed or curved. While Fig. 2 of the drawing shows only the upper and lower electrodes M as being curved, it will be understood that intermediate electrodes such as the electrode l5 may likewise be bowedor curved similar to electrode It. For purposes of simplicity in the drawing however, the electrode l5 and the remaining intermediate electrodes are shown as hat. The fiat electrodes may be of any suitable metal'or conducting material such as tinned brass or the like, but preferably the curved electrodes H are of a relatively thick springy material such for example as phosphor-bronze or the like.

As will be seen from Figs. 3 and 7, each electrode is provided .on its lateral edges with integral lugs I1 and I8 which are preferably offset with relation to each other for purposes to be described. Preferably also, the edge of each electrode opposite the lug I8 is cut away as indicated by the numeral l9. Lugs I1 and i8 are adapted to act as guides and bear against the inner faces of the side portions 3 and 4 as shown moreclearly in Fig. 3, thus preventing the electrodes from rotating when the condenser is being adjusted. For the purpose of preventing relative bodily sliding movement between the electrodes, each of said electrodes is provided at one end with an integral lug 20 which is under-cut at 2 l 22, so that the lug portion of the electrode may be removably interlocked with the bosses l, l or the bosses 8, 9 as shown in Fig. 3. For this purpose, it is preferred that the width of lug 20 between the under-cut portions 2!, 22, be approximately equal to the spacing between bosses I, 8 or bosses 8, 9. Thus these bosses cooperate with the lugs 20 to prevent relative sliding movement between the various electrodes, but at the same time the electrodes are interlocked to the base only at one end, and consequently the curved or bowed electrodes M are capable of being gradually flattened to vary the overall capacity of the condenser. Each of the electrodes is provided with a perforation 23 in order that the said electrodes may be assembled over the threaded member I3. Similarly each of the dielectric spacers 24 is provided with perforations 25. Preferably the perforations 23 are considerably larger than the diameter of member l3, so that when the electrodes are assembled they are entirely out of contact with the threaded member l3, and so that the curved electrodes may change their curvature without danger of contacting with the said member l3. For the purpose of adjusting and retaining the electrodes in their adjusted position, there is provided a screw 26 which passes through the internally threaded member [3 as shown more clearly in Fig. 2. An insulator washer 21 is positioned between the head of the screw 26 and the lower electrode 14, so that by turning the screw 26 which is threaded into the member 13, the curvature of the electrode 14 may be varied. It is to be noted, however, that while the screw 7 26 is being turned and since the curved electrode I4 is anchored at one end, the unanchored end of the electrode moves and in moving is guided by lugs H, I8 which slide against the edge portions 3, 4 as described above. Similarly a washer 28 is positioned between the threaded nut 29 and the upper curved electrode 14, so that by turning the nut 29 the curvature of the electrode I4 may be varied.

Preferably the blanks from which the electrodes are formed are identical in shape so that one blankmay be used for both electrodes. In order to reduce the creepage losses between the electrodes, alternate electrodes are preferably assembled in reverse direction. Thus for example, the electrode l5 may be assembled with its lug 20 between the bosses I and 8, with its lug H in engagement with the edge 3, and with its lug [8 in engagement with edge 4. The next superimposed electrode I6 is assembled with its lug 20 between the bosses 8 and 9 so that its lug I8 is displaced from the lug I1 of the underlying electrode and similarly with its lug l'l displaced from the lug.

l8 of the underlying electrode. When alternate electrodes are thus reversely assembled, the lugs 20 of corresponding electrodes are alladjacent to each other and may be connected together to form one terminal of the condenser. Similarly the lugs 20 of the other set of electrodes are all adjacent to each other and may be connected together to constitute the other terminal of condenser and ii desired, the extreme ends of the lugs 20 maybe bent at right angles to facilitate connection in circuit.

It is believed that the manner of assembly of the condenser will be obvious from the drawing and the above' description. Suflice it to say that by the arrangement disclosed the various electrodes and dielectric spacers are assembled in what may be termed for convenience, a cage, which cage is provided with a pair of locking grooves or rails at one end namely grooves 30, 3|; and a pair of guiding rails 3, 4, so that the bowed or curved electrodes are capable of longitudinal extension with respect to the fiat electrodes but are positively prevented from rotating when the adjusting members 26 and 29 are turned.

It will be understood of course that the invention is not limited to the utilization of alternate flat and curved electrodes since, if desired, all the electrodes may be bowed or curved. Furthermore, the invention is not limited tothe specific manner of assembling the curved electrodes, for example the electrode I4 may be assembled so that it prevents a convex surface to the adjacent dielectric member 24 and the member 28 may be elongated so that adjustment of the nut I 29 changes the degree of curvature of the electrode.

Various changes and modifications may be made herein without departing from the spirit and scope of the invention.

What I claim is:

1. An electrode assembly for a trimmer condenser including a pair of superposed metal plates each plate having a spacing lug on each longitudinal edge of the plates, the lugs on one plate being staggered with relation to the lugs on the superposed plate, each plate being also provided with a notched anchoring lug at one end, and with an edge notch, the edge notch on one plate being in alignment with the edge projection of the adjacent plate.

2. A variable condenser including-a base of insulation, a pair of spaced projections on said base, a pair of parallel guides on said base, a metal plate serving as a condenser electrode said plate having edge projections to slidably engage said guides the projection on one edge being staggered with respect to the projection on the opposite edge, another metal plate having a pair of staggered edge projections similar to those on the first plate, a dielectric layer between said plates, each of said plates having an edge notched adjacent an edge projection and the plates being superposed so that the notch on one plate is in alignment with the projection on the adjacent plate, and a lug extending from each plate and having its opposite edges notched to engage said spaced projections on the base.

, ALBERT E. PERRET. 

